Process and apparatus for testing electric meters.



E. M. WILKINS. PROCESS AND APPARATUS FOR TESTING ELECTRIC METERS. APPLIOATION-FILED 111111.20, 1908. RENEWED MAR. 18. 1911.

1 5,75. Patented Oct. 10, 1911.

ammo/14 1707 Edf'ar J71. Max 15m;

second. meter,

momentarily ,ters, comprises,

said second meter, and means, a heam, of light upon said mirror whereby.

MEXICO, \MEXICO.

PROCESS ANT), ATPARATUS F013. TESTING ELECTRIC METERS.

racemes.

Specification of Letters Patent.

Batented Uct. 10, 1911.

Originalg'application.filed August 12, 1907, Serial 1\To. 388,474. Divided and this application filed March 20,

1908; Serial No.

422,277. Renewed March 18, 1911.

Serial N 0. 615,386.

To all whom it may concern: I

Be it known that I, EDGAR M. WILKINS, a citizen of the United States of America, and resident of Mexico city, Mexico, have invented certain new and useful Improvements in Processes and Apparatus for Test-.

ingElectric Meters, is a specification.

This applicationfor a patentis a division of my former application, filed on or about August 12th, 19.07, Serial Number 388,474, an entitled, process and apparatus for testing watt-meters Patent The'in'vention herein set a process and apparatus for standardizing of which the following wattmeters.

The objects of the invention are to secure a saving of tlme over processes now in use,

and to secure such a degree of accuracy as is desirable'in practice.

Without regard to the various scopes of invention, which are. attended to in the claims, the statement of my invention is as follows: The process of comparing two rotary registering meters, one ofwhich has a spot or mark upon a rotating part thereof, consists in placing a fixed spot or mark so asto be viewed adjacent to said rotating spot or mark, arranging a mirror upon a corresponding rotating element of the setting said meters in rotation under the same load, directing a beam of light upon said mirror from such position that. its reflection: therefrom.- will be cast upon said first meter at a defithe rotating of the second, and

mte point in reflection in said mirror of the observing the successive angular positions of said rotating en momentarlly illuminated spot or mark wh by. saidreflected beam. p

'e apparatus for carrying outthe procfor com aring rotary in combination with; two of such meters to be compared, a spotor mark on the rotaryelement of one ofsaid meters, a or markin connection withwhicli its position 'inaybe measured a mirror mounted on the correspondingelement of for. throwi ess Number 905,966. forth relates to.

registering me said spot is momentarily. illuminated at a certain angular position of said' mirror.

he principles of my invention are well and clearlyillustratedin the accompanying drawing.

The single-figure of the drawing shows diagrammaticall the arrangement of the parts and electr cal connections for standardizing simultaneously or successively, a number ofalternating current service meters by means of a secondary standard, or standardized rotating-meter.

In the drawing every reference numeral and letter refers always to the same part.

The characters B and B designate the bus-bars or main conductors of an electric circuit carrying an alternating current.

The apparatus consists of a transformer Q having a high-tension primary 9, connected by leads g to the respective mains B, B and'its secondary g, which is-of few turns so as to give a large current at low tension, is divided bya plurality of taps 9 into a number of segments towhich correspond contact-bosses 9 disposed in a circular manner about the pivot of the contact-lever 9 which is so arranged as to connect any one of the bosses g with one pole of thecurrent-circuit R. The lever 9 may be constructed, with a pair'of contactfingers g and inductance g". The primary g of the transformer is tapped at one end 5 y a plurality of tape g which are brought down to contact-bosses 9 disposed for con fnection' with a contact l'ever 9 connected jto the lead g, In this way, the linernd yfustmentrof the current-circuit is provided;

I The secondary standard G showm'as disposed centrally'of a gro ofservice'- .imeters A which are-to be test or standard- ;ized. iOne ofthetermin'als of-the currenticoi l' of each. of: the meters A may, be permanently connected to one end of as seq;

, ondary winding" 'otthe "transformer lot or ends of 'sai 1 t l current-coils being .brought to the respective contact-bosses .9 Y

of a multi olar-sw1tchS, each boss thereof =correspond1ng to the current-coil terminal spot or mark a upon throw the light down in a .9 of the switch S; whereby the current placed on of one of the meters -A. The circuit "it passes from the contact-lever g through a continuously variable rheostat T, thence through the current-coils the circuit R passes successively through the rheostat T, the current-coil g of the standard G, and the current coils a of one of the service-meters A. Before making the test, the potential coils a 9' of all the meters are preferably connected up with the line by means of the leads 7), 5 so as to warm up the metersand have them innormal condition when the test is made. Each of the service meters Aris provided with a the disk thereof, and a stationary scale a placed adjacent thereto as shown in the drawing, this scale being preferably graduated in hundredths of a circumference each way fiom a central zeropoint as shown. At a convenient distance from the standard G is placed a telescope U or a focusing lamp V, or both, these being directed toward a small mirror g the shaft of the meter G. Both the telescope U and the lamp V are focused upon the scale a of any one of the servicemeters A, as indicated by the ray-lines a, it being understood, of course, that a second mirror may be used when necessary to vertical direction, as where the scale a is horizontal, being necessarily so represented in the dia ram. lt is also desirable to have a cylinrical screen or diaphragm W inclosing the meter G and having openings W and W therein in position to permit the passage of the light-rays between the mirror 9 and the telescope U, lamp V, andscale-disks a of the meters All .but one of these openings V may, to avoid confusion, be closed by diaphragms W While the meter corre sponding to the opening which is left open is being calibrated.

While the telescope and focusing-lamp are used conjointly, the light from the lat ter will be thrown instantaneously upon the scale of the meter being tested, when. the mirror g is in the roper angular position to reflect the light rom the lamp upon the meter scale. The light so flashed upon the scale will disclose the momentary position of the spot a observed through the telescope U, and the reflection being momentary, the spot will appearto be standing still at the given point on the scale. 11 the second revolution of the meter G, the same thing will take place, and if the meter under test is correct, the spot a will appear at the same point as before, and so on for successive revolution, whereas, it fast or slow, it will appear to move slowly oil to the right or left as observed through the telescope.

g of the standard -meter G, and thence to the contact-lever on the meter-disk, which is this case the rate or" acceleration or retardation may be measured, ii desired, and the meter set to the right speed by adjusting the control-magnets. As soonas one meter has been tested, the switch-lever s is shifted to start up the next meter which is tested in turn, and thus a large number of meters may be successively tested quickly, and without any change of adjustment of the testing apparatus other than above indicated.

In general, a suliicient accuracy according to this process by a single revolution of the shaft, another revolution having been first ,allowed the meter to rise from zero to normal velocity. Although more on the meter-disk for the purpose of testing in less than one revolution, 1 do not deem this advisable, as the rate-or rotation may be slightly dilierent from diderent parts of the revolution, making the first half, for example, appear longer orshorter than the second half. Where the telescope U alone is used (without the focusing-lamp) the meter-scales will be continuously illuminated, and where the focusing-lamp V is used alone, the position of the spot a may be observed directly upon the scale, being lrept in substantial darkness, except for the momentary illumination from the lamp V. In place of using the telescope U, the eye may be placed directly at this point, above or below the lamp V, and the mirror g it slightly concaved will present to the eye directed at the mirror a magnified image of the scale of shorter duration.

in the above manner, the meter A may be adjusted to correct registration at any given load, and the variations from correctness may then be tabulated by testing under any other load; Even where the loadcharacteristics of the service-meters are the same as the standard by which they are tested, (which will be the case if they are of the same type and capacity) it is generally advisable to test them at two loads one heavy and one, light, as casual defects, such as undue friction of bearings, gear-train, etc., can not otherwise be detected.

While some of the features herein described are limited tothe uses of alternating current, it will be understood that in general, the system is applicable to any kind of current, and polyphase connections, for er.- ample, can readily be devised by those skilled in the art..- 1 do not consider my invention limited in its form a scope of modificationotherwise than may be inferred from the reasonable construction of my claims.

I claim as my invention z--- meter can be tested with than one spot might be used l. lhe process ozt comparing two rotary registering meters one of which has a spot or mark upon a rotating part thereof, and

' same load, directing a flection therefrom will placing a, ;fixed spot or mark adjacent to the path of said rotating spot or mark, whereby upon apart rotating in the same period, set-' ting both meters in operation under the same load, and observing in said mirror the momentary reflection of the successive posit-ions ofsaid rotating spot or mark relative to saidLfixed spot or mark, whereby con clusions-may be derived as to the relative rates of rotation of said meters.

2.,The process of comparin rotary registering meters one of which as a spot or markon a rotating element thereof, and a fixed spot or mark so as to be viewed adjacent to said rotating spot or mark, a mirror upon a correspondin rotating element of the second meter, said process consisting in setting said meters in beam of light .upon position that its rebe cast momentarily upon said first meter at a definite pointin the rotating of the second, and observing said mirror from such the reflection in said mirror of the successive angular positions of said rotating spot or mark when momentarily illuminated by said reflected beam.

3. An apparatus for comparing rotary registering meters comprising, in cofnbination with a spot on a rotating element of oneof said meters, a fixed spot or mark in connection with which its position may be measured, a

mirror mounted on the corresponding element of said second meter, and means for throwing a beam of light upon said mirror meters, a fixed spot or rotationunder the" two of said meters to be compared,

whereby said spot momentarily, illumi- 40 nated at a certain angular position of said mirror.

4. An .apparatus for comparing rotary registering meters comprising, in'combination, with two of said meters to be compared, a spot on a rotating element of one of said mark in connection with'which its position may be measured, a mirror mounted on the corresponding element of said second meter, and means for observing the reflection in said mirror upon a fixed point at a distance therefrom'of the momentary position ofsaid spot-or mark at the moment of each revolution of the second meter when said mirror is in proper position to reflect it.

5. An apparatus for comparing rotary registeringmeters comprising, in combination with two of such meters to be compared, aspot or mark on the rotary element of one of said meters, means for measuring its angular position from a fixed point, a mirror mounted on the corresponding rotary element of the other meter, means for placing thesame load on both'meters, adevice for throwing a beam of light against saidmirrorin such direction that it is refiected'momentarily upon saidspot' or mark in'a certain angular position'of said mirror,

and a sighting device such as a telescope,

arranged in line with said illummatm device to receive the reflection in said mirror of said spot at the same moment as illuminated by said illuminating device.

EDGAR M. WILKINS.

Witnesses:

A. ALLARD,

R. J. Rama. 

